#include <cstddef>
#include <iostream>
using namespace std;

int main(int argc, char* argv[])
{
    const char* key = (argc > 2) ? argv[1]:"";
    size_t key_len = (argc > 2) ? strlen(key) : 1;
    char input;
    int i = 0;
    while(cin.get(input)){
        input ^= key[i];
        i = (i+1) % key_len;
        cout.put(input);
    }
}

        
